This project consists of two distinct parts: One is the exact determination of the composition/structure of several adjuvants and adjuvant formulations (i.e. 1-O-Octyl-B-glucoside, oil in water emulsions, QS21, MPL and Alum). The second part is the examination of the use of polysaccharides microspheres as a vaccine delivery system. A critical component for both parts is the determination of structure and function of the different formulations. Since these are molecular ensembles, some of the most important physical characteristics that need to be determined is size and size distribution. For that reason we have undertaken to setup a Multi Angle Laser Light Scattering (MALLS) facility with the capability of measuring sizes ranging from polymeric molecules to particles in the micron range. We have so far setup and validated the photometer for its ability to measure weight and size distributions of macromolecular ensembles by fractionation with size exclusion chromatography or Asymmetric Field Flow Fractionation (AFFF) and measurement of size with MALLS. We are in the process of developing the technique for fractionating large particles and emulsions with the AFFF. Preliminary work has demonstrated that we can obtain information on the solution behavior of adjuvants both through the measurement of their change in refractive index with concentration (where marked shifts in the slope of the dn/dc lines have been observed) and in a direct measurement of molecular weight with AFFF-MALLS. This capability will allow us to complement our NMR and computational modeling work in giving us a detailed understanding of the solution interactions of adjuvants and antigens.